Timeline: Mounting evidence for a wet Mars

The one giant question remaining is the one people are the most interested in. Is there any liquid water on Mars today? We might learn the answer in 2005 if all goes well with the MARSIS radar mapper aboard the European Mars Express orbiter.

MARSIS will be able to find signs of water as deep as 1 kilometre below the surface. If there really is a geothermally heated water table below the surface, or even just a few deep geothermal water pockets, they should show up clearly. MARSIS still won't tell us whether there is life on Mars. But it certainly will tell us where to look.

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As NASA's Mars Exploration Rover Opportunity creeps farther into "Endurance Crater," the dune field on the crater floor appears even more dramatic. This false-color image taken by the rover's panoramic camera shows that the dune crests have accumulated more dust than the flanks of the dunes and the flat surfaces between them (Image: Cornell / JPL / NASA)